In the early 1970s, concern began to be expressed that the stratospheric ozone layer (which provides protection against penetration of the Earth's atmosphere by ultraviolet radiation) was being depleted by chlorine atoms introduced to the atmosphere from the release of chlorofluorocarbons. These chlorofluorocarbons were used as propellants in aerosols, as blowing agents for foams, as refrigerants and as cleaning/drying solvent systems. Because of the great chemical stability of fully halogenated chlorofluorocarbons, according to the ozone depletion theory, these compounds do not decompose in the Earth's troposphere but reach the stratosphere where they slowly degrade liberating chlorine atoms which in turn react with the ozone.
Concern reached such a level that in 1978 the U.S. Environmental Protection Agency (EPA) placed a ban on nonessential uses of fully halogenated chlorofluorocarbons (CFC) as aerosol propellants, and in 1995 banned nonessential uses of hydrochlorofluorocarbon (HCFC) propellants.
There is also a demand for aerosol propellants which have significantly less photochemical reactivity than hydrocarbons that contribute to the formation of ambient ozone and ground level smog. These compounds are typically referred to as low-VOC (volatile organic compound) or non-VOC.
The disclosure herein relates to the discovery of compositions, which include unsaturated fluorocarbons and hydrofluorocarbons. These compositions have zero ozone depletion potential (ODP), low global warming potential (GWP) and are lower VOC than hydrocarbons. These compositions are useful as pure components or in mixtures. These compositions are used as aerosol propellants.